One man, one small business, four billionaires

Entrepreneur Jordan Eisenberg came up with a business idea that has drawn investments from four billionaires: Sam Zell, Herb Simon, David Bonderman and, as Eisenberg put it, "one family you've never heard of—who'd think there's a billionaire you've never heard of?"

Eisenberg created UrgentRx, a Denver-based company that sells single-dose generic medications for everyday health problems like headaches and indigestion.

What's novel about the company, though, is the visible shelf space it's been able to use without paying the usual high costs associated with displays. Instead of vying for traditional space next to well-established brands, Eisenberg has created his own custom-designed displays for areas where there's been nothing at all—essentially wasted space.

For example, an UrgentRx display might be a small Lazy Susan spinning atop a pole in the pharmacy line, or it might hang off the side of a cart. "We've become not only an innovative over-the-counter company," Eisenberg said, "we've become an innovative merchandising company."

A UrgentRX dispenser machine at Denver's Mile High Stadium.

UrgentRX's big break happened about a year ago, when Eisenberg went to a trade show and sold his idea to drugstore chain Duane Reade, owned by Walgreen.

The drugstore decided to take a chance on the idea, figuring that handy, on-the-go relief might be perfect for its busy New York customers.

UrgentRX has since grown from a presence in 1,000 stores to 20,000, including many Walmart and CVS stores, with a full rollout at Walgreen and Rite Aid planned for 2014. This month, it launched displays on the carts that flight attendants use to serve beverages on Allegiant Air, selling quick fixes for bad digestion or headache medicine if, Eisenberg said, "you're coming back from Vegas and you've overindulged."

The company also landed a deal selling meds at displays inside Denver's Mile High Stadium.

UrgentRX has raised $10 million and hopes to do $3 million in sales this year. Eisenberg has used much of the money to build inventory using a manufacturer in Utah, a state considered the Silicon Valley of over-the-counter health-care products. He's also contracting with a second manufacturer in the Northeast.

The company has filed patents on all of its displays, and in the first quarter of 2014, Eisenberg hopes to raise another $12 million to $15 million to start a national marketing campaign.

"I want this to be a ubiquitous brand, that people will think, 'When I need fast relief, I'm going with UrgentRX.'"

If Eisenberg sounds confident, he had to be in order to reach investors with big money. How does an entrepreneur from Denver get investor and real estate mogul Sam Zell on the phone?

Eisenberg said he never stopped working his contacts and kept moving up the financial food chain until he could get a billionaire willing to listen. When the call came, it was brief.

"They want to get down to business," Eisenberg said. "There's not a lot of fluffy chitchat."

Eisenberg did not say who the fourth billionaire investor is. He did say said Zell helped bring OTC veteran Michael Valentino onto UrgentRX's board. The New York Times reports that even actress Hilary Swank has invested.

What's next? Besides the marketing campaign, the CEO hopes "to double or triple" the number of places where UrgentRX is sold in 2014, continuing to use spaces no one else has noticed.

"The biggest challenge is that the retail marketplace is just not designed to work with new companies," he said, While many retailers talk about reaching out to new players, he said, "when the rubber meets the road, it's very difficult."

—By CNBC's Jane Wells. Follow her on Twitter Follow her on Twitter @janewells